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5 also perfectly homogeneous.

UNITE STATES ATENT DFFICEE;

AMBROSE Gr. FELL, OF NEW YORK, N. Y.

MANUFACTURE OF LEATHER FROM ARTIFICIAL SKIN.

SPECIFICATION forming part of Letters Patent No. 262,584, dated August15, 1882.

Application filed December 5, 1881. (Specimens-l To all whom it mayconcern:

Be it known that I, AMBROSE G. FELL, of New York city, in the county andState of New York, have invented a new and useful 5 Improvement in theManufacture of Leather, which improvement is fully set forth in thefollowing specification.

This invention has for its object the manufactnre of a new kind ofleather, which in its To physical or chemical characteristics shall'besimilar to if not identical with that ohtainedfrom the'skins of animals,and applicable to the same uses, differing therefrom only in itschemical constituents, and in that but slightly. This leather is nottermed artificial, which might imply inferiority, whereas in somerespects this new leather is superior to the ordinary material, Thematerial from which my leather is prepared may be termed 2o artificialskin but the leather itself is real leather, for leather, whetherproduced by the old method of treating hides or by the new processhereinafterdescribed,"is for all prac- 'tical purposes and in chemicalparlance identi- 2 5 cal, consisting of an insoluble, imputrescible,tough, homogeneous sheet of gelatinous tissue or fiber.

In the processes of making ordinary leather the skin of an animal,having been deprived of its extraneous matter by the usual methods, andbeing ready for conversion into the leather of commerce,consists of aweb or tissue of fiber filled in with a substance chemically known asosseine, and the processes of tanning, to 3 5- which said skin isafterward subjected, are twofold in their object, first, to convert theosseine into gelatine by a rearrangement of its chemical atoms, and,second, to combine the fiber with the gelatine thus produced,forming theinsolu-' 4o bleimputrescible material known as leather.

In the present invention, instead of the natural homogeneous sheet offiber and gelatine known as skin, a sheet of fiber and gelatine isprepared, as hereinafter described, which is The improved process,however, affords the great advantage of a choice of fiber best adaptedfor the intended uses of the ultimate leather, and another advantagegained is the uniformity of the productinthicknessandstrength. Unless inthe course of preparing the substitute for skin some agent is introducedto take the place of subsequent tanning, the process of treatment mayproceed in the ordinary method of converting skin into leather-that is,the arti- 5 5 ficial skin is subjected to the action of such chemicalsas shall render its gelatine insoluble, imputrescible, flexible, and soon. The means employed for this purpose may be any of those ordinarilyused in treating natural skins for the same purpose. It is preferred,however, to use the method hereinafter specifically described.

The object of the present invention, then, is to produce a leatherwhich, while possessing all the desirable characteristics of thatprepared from the skins ofanimals, shall, in ad dition thereto, beuniform in thickness and strength and capable of being made in large orcontinuous sheets with straight edges,which .will enable it to be cut tomuch better advantage than is possible with the "irregular outline of askin.-

In carrying my invention into effect I proceed as follows: A homogeneouspulp of fiber and gelatine is formed by any convenient means, employingany description of fiber, but preferably the long fiber of raw cotton.Now, if simply coating said fiber and filling up the interstices thereinwasall that the process aimed at, this could be effected by simplydipping, washing, or other application of the gelatine to said fiber;but the object of this process is to effect the combination of the fiberand gelatine into one homogeneous mass, in which the identity of thefiber or tissue is for the time being lost, in the same manner as thefiber of a natural skin is lost previous to tanning. This marks thegreat difference in the first step of my process as distinguished from 0the ordinary processes, in which the fiber is merely steeped in ortreated by a gelatine compound.

Fiber, whether animal or vegetable, will mix with gelatine solution; butby reason of the atmospheric air, oleaginous, andother elements whichoccupy the interior of each individual fiber the gelatineis preventedfrom doing more than merely surrounding said fiber, and this only withdifficulty; but by expelling the air I00 and foreign matter from thefiber an intimate and homogeneous union is effected. With this object inview the fiber is first subjected to the action of boiling water orchemical solution, and having thus displaced the air and other elements,and while it is still wet and hot from said treatment, it is admixedwith the gclatine compound, with which it will now gradually andcompletely combine.

The artificial skin or mixture of fiber and gelatine is preferablyformed as follows: I take raw cotton or wool or any other loose fiber,and by suitable means form it into a light fiuft'y web. If cotton is thefiber chosen, it is formed into such a web by means of a machine similarto that usually employed to form cotton-batting; but for the purposes ofthis process the cotton or other fiber is kept as loose as possible, theWidth and length of said web being governed by the width and diameter ofthe drum employed in said machine; or the fiber may be run off incontinuous lengths, as hereinafter shown, and the thickness of the webis regulated by the amount of cotton allowed to accumulate on said drum,as well understood in the art. The cotton deposited on the drum of thebatting-machine is very loose and tender, and cannot be rolled uponitself; nor can it be unrolled without losing its uniformity ofthickness. The web from the batting-machine is therefore rolled on someother material, that known as burlaps answering the purpose very well.To accomplish this I provide aroller in front of the batting-machine,and to this roller is conducted one end of the burlaps, and on this thecotton-fiber web from the machine is laid by revolving the roller, the

cotton web and burlaps-being wound together thereon, so that a thicknessof burlaps will be between each layer of fiber. Care should be taken notto wind the web of fiber too tightly, as by so doing it would retard thesubsequent process. The burlaps should be alittle wider than the sheetofv fiber and the roller a little longer than the width of the burlaps.

A sufficient length of fiber being wound, the roll is secured fromunwinding by tying with cords-say at twelve inches apart-or in anyconvenient way, care being taken not to com press the rolltoo tightly.The roll is then placed in a bath of boiling water, the object of whichis to thoroughly saturate the fiber therewith and displace all theatmospheric air and foreign matter contained in said fiber, for if suchresult is not accomplished either by these or other means it will befound very difficult, it not impossible, to effect a completecombination of the fiber with the gelatine, which issubsequentlyapplied. Theboilingshouldcontinue for one or more hours,according to the thickness of the fiber-web and the size of the roll.After the boiling has continued a sufficient time the roll is removedfrom the bath and allowed to drain until most of the water that will runoff has done so. The roll is next placed in a bath composed of water,gelatine, and bichromate of potash. The proportions are not material,and may be varied within wide limits but for general practical results Iemploy the following: water, six gallons; gelatine, eightpounds; andbichromate of potash, three per cent. of the gelatine. The bichromate ofpotash may be left out at this stage and subsequently applied, and inlike manner other agents employed in subsequent steps of the process maybe here introduced with advantage under some circumstances. The objectof the chromic salt is to render the gelatine more or less insolublewhen exposed to light, or by subjecting it to a high temperature or bylapse of time.

It is obvious that instead of having a separate vessel for the secondbath the fluid composing the first bath could be drained off and thesame vessel used for the second bath; but it is preferred to proceed inthe manner described. As to the character of gelatine employed, althoughthat known in commerce as glue answers the purpose well, still, as thestrength and durability of gelatine is greatly affected by hightemperature and by frequent dissolving, it is preferred to obtain thegelatine direct from any of its sources of production, and while stillin solution to apply it di rectly to the purposes oft-he presentrocesses, thus obtaining a stronger and more durable result. The roll isallowed to remain in this second bath, which is heated to a temperatureof about 120 Fahrenheit for two or more hours, or until the water withwhich the fiber has been previously saturated is completely replaced bythe gelatine compound. The roll is then removed and allowed to drainuntil most of the surplus liquor runs off. The fiber, saturated andcombined with the gelatine, is next placed upon a sheet of glass orother material, upon which it is unrolled, so as to bring thegelatinized fiber next to the surface of the sheet or slab. Suflicicntpressure is now brought to bear upon the burlaps to force the gelatinousmass into as close contact as possible with the glass or other surface.The fiber and gelatine are now in the condition of a sheet ofpulpyjelly, and if the fiber has become thoroughly combined with thegelatine it at this stage is almost indistinguishable therefrom,having'been rendered more or less transparent by its union with saidgelatine.

If a solid and compact leather is desired, more of the gelatine compoundis poured over the burlaps and spread evenly thereon, and it will runthrough said burlaps and mingle with the gelatinous mass spread beneathit, increasing the proportion of gelatine therein. The burlaps can now'be removed. The gelatinous fiber, however, is allowed to remain on theglass orother surface until dry, which will require twelve hours ormore, according to the thickness of the material, temperature, andventilation. tion of the gelatinized fiber as it is placed on the glassslab is such that it cannot be well brushed or rolled without disturbingthe uniformity of its arrangement, and hence the no- The semi-liquid andpulpy condi- IIO cessity of the sheet of burlaps or other material as anintermediate means to allow of distributing the gelatine compound pouredon as described. A further degree of solidity can be added to thematerial by again treating it with the gelatine compound after dryingand still further increased pressure.

As a material on which to spread the gelatinous fiber, I prefer glass orother translucent material, so that light can penetrate as well to thelower as to the upper surface of said gelatinous fiber, which, by reasonof the presence of the chromic salt contained in the gelatine, rendersit insoluble. The exposure to light should be continued after thematerial has become dry, for it is while dry that the insoluble effectis most readily and effectually produced. The color of the light is alsoimportant, as, should the color be blue, for instance, the action willbe slow; if yellow, the action will be almost entirely arrested. A material void of color is therefore most desirable, white glass beingbest.

\Vhen glass is used as the surface on which the gelatinized fiber isspread the latter, after it is removed from such surface presents twosurfaces distinctive in their character, that which was next the glassbeingsmooth, compact, and not inclined to shrinkwhen dampened andredried, and the upper surface being even butnotsmooth,andliabletoshrinkwhen dampened and redried. In this respect the material corresponds withthe skin of an animal,

- the smooth side representing the outer or grain side, and the othercorrespondin g with the flesh side of a natural skin. When anontransparent slab is used upon which to spread the gelatinous fiberthe latter should be exposed to the light after drying and removal fromthe slab.

In drying the mass of gelatinous fiber will be found to have become moretransparent and greatly lessened in thickness, the whole of itscontraction being in that direction, thereby securing a greater amountof strength in proportion to its thickness. It moreover adheres verytenaciously to the surface on which it is dried. To remove it, however,it is only necessary to moisten the material by washing, immersion,sprinkling, or in any convenient way until softened through its entirethickness, when its removal is readily effected. lVa-ter will answer forthe purpose; or, if a greater degree of insolubility is required, asolution of alum or other material capable of producing the desiredeffect may be used. If, however, the chromic salt or its equivalent wasnot admixed with the gelatine compound comprisingthe second bath, thenthis stage of the process affords a convenient opportunity for itsintroduction. A solution of said salt containing, say, three per cent.of bichromate is used for softening the artificial skin as it lies uponthe slab upon which it was dried. When sufficiently moistened it iseasily removed by rolling up or in any other,

applied the artificial skin should then be exposed to light for a fewhours; but if water is used as the medium of removal the skin may beimmediately placed in the third bath of tanning preparation referred tobelow, though agreater degree of compactness is assured by drying itbefore subjecting to the final bath; or, if the gelatine contains or hasbeen treated with the chrome salt or its equivalent, and thus renderedinsoluble and imputrescible, the leather at this juncture may becompleted by simply rendering it opaque and flexible by soaking in asolution of lead acetate, and next in a solution of any carbonatesaycarbonate of soda or one of many other methods may beemployed. Forsuppleness glycerine may be added in the last-mentioned step or at someother stage.

Instead of boiling the roll of fiber in water as the initial step in theprocess, a solution may be employed of alum or salt of iron or any agentcapable of rendering the gelatine subsequently employed more insolubleor to facilitate the displacement of the air; or the first bath may bedispensed with altogether, and the fiber instead may be placed in anair-tight vessel and the air exhausted therefrom, and the second bathmay be applied to the fiber while in the vacuum or any other means forremoving the air and other contents of the fiber may be employed.

The artificial skin prepared by the process above described is atransparent sheet of gelatinized fiber in a homogeneous mass, the fibertherein being indistinguishable from the gelatine, and this artificialskin bears so close a resemblance to a natural skin, both in appearanceand nature, that it may be finished by any of the methods employed fortreating skins of animals to produce leather, or with very slightmodifications of said treatment. Moreover, in finishing the leather bythe ordinary method-it will be found that it is not affected, as isthecase with the natural skin, by elevation of temperature. Hence thetanning solutions wherewith it is treated may be employed at a highheat, and thus effect in a few hours what would otherwise requireseveral days. If, however, a porous and spongy leather is required, itis preferred to allow more time at a lower temperature.

The tanning preparation for the final treatment is preferably composedof water containing equivalent to, say, five per cent. of tannic acidand twenty-five per cent. of glycerine or other agent capable ofimparting flexibility. The tannic acid may be added as such; orbark,sumac, nut-galls, or any other compound or material containing tannicacid or its equivalent may be used instead; but the invention is notlimited to the use of tannic acid, since any other agent, material, orcompound now known'and used for producing the result understood underthegeneral terms of tanning and Ftawing may be used instead.

Owing to the aforementioned peculiarity of convenient way. When thechrome salt is thus the contractibility of one side of the artificialIIO skin and the incontractibility of the side next to the surface onwhich it was dried, this leather may be grained in like manner to anatural skin, so that when the material is rolled and rubbed, asunderstood in the method of graining, the one side contracts and theother side wrinkles to accommodate said contraction, the form of saidwrinkles being governed by the direction in which the skin is rolled andmanipulated, according to the skill of the operator. The peculiarityofthese wrinkles constitutes the difi'erent styles of graining, as wellunderstood in the art.

Many modifications of the process may be made with desirable results,according to the purposes for which the finished leather is intended.For instance, when the gelatinous fiber is placed on the surface onwhich it is intended to be dried no additional gelatine solution need beadded, in which event the artificial skin, when dry, will be less solidand more spongy and soft.

If a finished leather is desired of such thin ness as is impracticableto produce from so frail and tender a web as that formed with the fiberemployed, the following process can be used: Proceed in the mannerindicated with the production of the sheet of gelatinous fiber, andplace it on the slab of glass or other material, and upon this bring anyconvenient pressure, as by a roller, which tends to concentrate theamount of fiber in the body of the artificial skin and forces a largerproportion of gelatine to the two surfaces. Now, when the skin isremoved, as set forth, and while still wet, it will with care evenlysplit, the concentration of the gelatine on the surfaces strengtheningthem, and causing the material to split in the middle, where weakest.Having thus secured as thin a skin as desired, it can be tanned, tawed,or finished by any method in this condition or after application ofadditional gelatine to its split side, according to the kind of leatherrequired.

Any thickness of leather may be secured by regulating the thickness ofthe fiber first employed or by uniting two or more layers of thematerial at any stage of the process most convenient. The character ofthe leather may also be varied by removing from the surface on which itis spread while still wet or by drying direct from the roll. In bothcases it will not have a smooth or grain side, but two porousorfieshsides. Thesemaybemadesmoother by coating with the gelatine compound;but, as will be readily understood, the coating thus applied does notform a homogeneous mixture with the body of the leather. If the gelatinecompound thus applied to the surface is colored and the material, whilestill damp, brought in contact with a glossy surface and allowed to drythereon, the surface of the finished leather will resemble the ordinarypatent or enameled leather.

One feature which the leather made according to the above processpossesses in common with leather made from animal-skins is itselasticity when stretched in any direction, especially when damp.- Thisproperty is due to the homogeneous combination of unbroken separatefibers with the gelatine, which property could not be had with abrokenfiber, as in paper or the pulp whereof it is made, which latter isnot adapted to this process, or with a woven or spun fabric, where thewarp or woof would be opposed to such elasticity.

It will be understood that by forming a homogeneous mixture of fiber andgelatine it is not meant that the former is dissolved, so that itsidentity as fiber is destroyed, since if this were the case theresulting product would not be true leather, in which the fiber,fibrine, or tissue, although being one substance intimately butmechanically mixed with the gelatine, possesses its individual existenceand imparts its structural characteristics as fiber to the finishedarticle.

In conclusionI would observe thatI am aware of Letters PatentoftheUnitedStatesNo.38,785, No. 94,080, No. 153,473, No. 210,079, and No. 247,635,which show the use of gelatine with a tanning agent, either without theuse of any fiber whatever or with the use of paper or a textile fabricto the surface of which the composition containing gelatine is applied.1 am also aware of Letters Patent No. 129,217, in which tanno-gelatineis used as a solvent of cellulose, so as to form an elastic gummy mass,which becomes hard, like horn, when thoroughly dried, the cellulosebeing used in the form of ordinary paper pulp or raw cotton orotherwise; or starch is used in place of cellulose, it being in itschemical composition isomeric with cellulose, thus producing aninsoluble hard compound. None of these patents show my invention, and Idisclaim what is shown in each of them. None of them show a homogeneouscompound of unbroken separate fibers with gelatine, said fibers beingneither woven nor spun, as is the case with textile fabrics, nor forminga compact mass of minute broken fibers, as where paper is used. Theleather made by my invention is like the leather made from naturalskins, in that it contains numerous ramifyin g fibers intersecting oneanother in every position, and not attached together in the form ofeither thread or warp and woof, which would effectually prevent theproduct having the elasticity in every direction, the capacity of beingsplit, and of having its end skived-that is to say, fastenedso as to beof even thickness, by shaving the overlapping edges to a bevel andfastening them in the manner familiar in belting, &c., which are amongthe properties which render natural leather so valuable a substance. Inmy leather, as in the natural leather, the fiber is not dissolved in thegelatine or chemically combined therewith; but the fiber and thegelatine form a homogeneous mass, precisely as in the natural leather,thus clearly distinguishing it from all so-called artificial leather ofIIO which spun fibers or woven fabrics form a portion.

Having now fully described the nature of my said invention and explainedthe manner in which the same may be. carried into effect, what I claimis- 1. In the manufacture of leather, the method of forming ahomogeneousmixture of fiber and.

gelatine by displacing the air and other foreign substances from saidfiber and applying thereto the gelatine or a compound thereof,substantially as described.

2. In the manufacture of leather, the method of producing an artificialskin or web by boiling cotton or other fiber in water or a suitablesolution, as indicated, and applying to said fiber gelatine or acompound thereof, substantially as described.

3. In the manufacture of leather, the method of forming an artificialskin or web by boiling cotton or other fiber in water, applying gelatinethereto, treating said fiber with bichromate of potash or itsequivalent, and exposing to light, substantially as described.

4. The method of forming a homogeneous and insoluble compound of fiberand gelatine, consisting in displacing the air and other foreignsubstances from said fiber, applying gelatine thereto, treating withbichromate of potash or its equivalent, and exposing to light,substantially as described.

5. The method of producing an artificial skin or web by boiling cottonor other fiber in water or a solution, then treating said fiber in abath composed of water, gelatine, and bichromate of potash, inapproximately the proportions specified, drying the gelatinized fiberthus formed on a smooth slab or surface, and exposing to the action oflight, substantially as described.

6. The method of producing an artificial skin or web by forming ahomogeneous compound of fiber and gelatine in substantially the mannerspecified, and spreading said compound to dry upon a sheet of glass orother translucent substance, substantially as described.

7. In the manufacture of leather, the method of producing an artificialskin or web by treating fiber while in a roll between burlaps or othermaterial in a bath of boiling water or solution,and in asecond bath ofgelatine compound, then unrolling the gelatinized fiber thus formed upona sheet of glass or other material, and allowing it to wholly or partlydry thereon, substantially as described.

8. The improvement in the art of manufacturing leather, consisting intreating fiber in a roll between other material witha gelatine compound,spreading the gelatinized compound upon a suitable surface, asexplained, and applying additional gelatine thereto, substantially asdescribed.

9. The improvement in the art of manufacturing leather, consisting informing a homogeneous mixture of fiber and gelatine, spreadin g the sameupon asuitable surface and subapplication of moisture, substantially asdcscribed.

11. The method of producing a colored or enameled surface upon a sheetor web of gelatinized fiber, such as described, by applying a layer ofcolored gelatine thereto and drying in close contact with a smoothsurface, substantially as set forth.

12. In the production of an artificial skin for the manufacture ofleather, the method of treating fiber to exclude the air and otherforeign substances therefrom by immersing in a bath of boiling water orsuitable solution, as described.

13. Leather composed of a homogeneous mixture of fiber and gelatine,substantiallyas described.

14.. As a new article of manufacture, leather composed of a homogeneousmixture of fiber and gelatine, rendered insoluble by treatment with achromic salt and exposure to light, substantially as described.

15. Leather composed of fiber and gelatine, and having an enameledsurface, substantial- 1y as described.

16. Leather composed of a homogeneous mixture of fiber and gelatine, andhaving two distinct surfaces corresponding respectively to the fiesh andgrained sides of leather made from natural skins, substantially asdescribed.

17. The process, substantially as described, of making leather byhomogeneously combinin g gelatine and fiber to form an artificial skin,and then tanning the same.

18. Leather composed of gelatine and fiber homogenously combined so asto form an artificial skin, and subjected to the process of tanning,substantially as described.

19. The process, substantially as described, of making leather byhomogeneously combinin g gelatine and fiber to form an artificial skin,and then tawing the same.

20. Leather composed of gelatine and fiber homogeneously combined so asto form an ar tificial skin, and subjected to the process of tawing,substantially as described.

21. The process of forming an artificial skin by homogeneously combiningfiber and gelatine, substantially as described.

22. Artificial skin formed by homogeneously combining gelatine andfiber, substantially as described.

23. The process of making leather, substantially as described, bycombining gelatine and fiber to form an artificial skin, the same beingacted upon by chromic acid or its compounds, substantially as described.

24.. Leather composed of gelatine and fiber homogeneously combined so asto form an ar- 5 tificial skin, and acted upon by chromic acid or itscompounds, substantially as described. 25. The process of makingleather, substantially as described, by homogeneously combinin ggelatine and fiber to form an artificial skin, 10 the same being actedupon by chromic acid or its compounds, and then tanned or tawed, as setforth.

26. Leather composed of gelatine and fiber homogeneously combined so asto form an ar- I 5 tificial skin, and acted upon by chromic acid A. e.FELL.

Witnesses:

WILLIAM P. LEGGATT, J OHN MOCLURE.

